Networked facilities management system with time stamp comparison for data base updates

摘要

A networked system having a wide variety of applications and particularly applicable to facilities management systems has multiple levels of software in processing nodes. The levels include a "features" processing level which communicates requests for data to a software object level containing databases of processes and attributes and database managers. The database managers in the software object level operate to provide data to the high level features in the same format. The software object level communicates with a hardware object level which also contains databases and database managers to mask differences between operational hardware units. By categorizing operational units by type, additional units of a known type can be added with only low level hardware object database changes. Adding units of a new type is facilitated by software changes confined to the lower level hardware and software objects, avoiding software changes at high level features. Individual software objects are tailored for typical types of inputs and output devices encountered by facilities management systems. Universal drive circuitry also provides applicability to a broad range of devices. In each node a time stamp indicates the most recent update of the node's data base. Periodically each node transmits its time stamp. When a node receives a time stamp later than its own, the receiving node requests the transmitting node to transmit its data base to update the receiving node with the earlier time stamp.